1. Field of Invention
This invention relates to a lead-acid type of battery charger.
2. Brief Description Of The Prior Art
Battery charging is a very active art and there are various types of batteries which are rechargeable. The invention herein relates to automotive type of lead acid batteries.
There are various ways disclosed in the prior art in charging a battery to control the charging operation and to determine that the battery is fully charged. Reference is made to related prior art U.S. patents to indicate what has and is being practiced.
In U.S. Pat. No. 4,853,607 provision is made to sense a full charge and provide a trickle charge to maintain it.
Practiced in U.S. Pat. No. 4,755,735 is the application of a high rate charge based on a time interval and not by control of voltage.
In U.S. Pat. No. 4,673,862, the battery is charged by repeated charging cycles each followed by a testing period to determine the state of the charge.
In U.S. Pat. No. 4,667,143, there is provision for charging a battery at a voltage compared with a reference voltage which varys with the temperature of the battery.
A constant current is provided in U.S. Pat. No. 4,636,704 which controls the charging current and is stopped by a signal element upon completion of a charge.
Temperature compensation is provided in U.S. Pat. No. 4,220,908 which falls linearly with a rising temperature to control output charging voltage.
In U.S. Pat. No. 4,394,612, a voltage comparator monitors a reference voltage to determine if the full charge circuit should be in operation and further provides a trickle charge to maintain a full charge.
Used in U.S. Pat. No. 4,341,988 is a voltage level detector and a control circuit responsive to the output of a voltage comparator controlling the charging in response to the battery voltage attaining a maximum desired level.
In U.S. Pat. No. 3,600,661, a temperature compensating means embodies a voltage regulation means using the regulated voltage to control the charging circuit applied to the battery with dependence upon the temperature present.
In 4,241,523 there is provision for controlling the battery charging rate relative to the battery temperature by the use of a resistance unit to control the charging rate.
There appears to be no particular specific practice of charging a battery in the reviewed art, however, one omission which stands out seems to be a lock of effort to control the charging output voltage and to regulate the charging voltage to be constant.
It is desirable to have means to automatically control the charging or output voltage within specific limits whereby the electronic components of an automotive vehicle will not be adversely affected by any overcharging of the battery.